Issue link: https://www.e-digitaleditions.com/i/1066130
34 I ICT TODAY 5 4 MASSIVE MIMO AND 4X4 MIMO 5G will enable the connection of many more devices to the network. Consequently, 5G will require ample capacity to support the massive volumes of data passing through the network. This is where and why massive MIMO and 4-by-4 MIMO will play an important role. MIMO is defined as "Multiple In-Multiple Out" and it simply refers to multiple antennas that send and receive wireless signals in order to provide more capacity and faster speeds. MASSIVE MIMO essentially constitutes a lot of antennas at a base station serving many users simultaneously. A recent iBwave whitepaper suggests that 44 antennas may reside inside a single panel 3 rather than the one or two antennas that are commonly found inside panels today. Because this technology will increase capacity for base stations at cell towers, massive MIMO will be deployed mainly for outdoor coverage. It will not likely be deployed for in-building networks due to the sheer size and cost. 4X4 MIMO, on the other hand, will be deployed for in-building networks. In fact, 4x4 MIMO is already being designed and deployed for some in-building networks. 4X4 MIMO is similar to a present-day MIMO system, except instead of having two infrastructure layers, it has four layers: four headend units, four remotes, and, consequently, four cable runs from the remotes to the antennas for each sector. 4X4 MIMO can provide much more capacity to serve tomorrow's wireless needs throughout many venues. CBRS Citizens Broadband Radio Service (CBRS) uses time division LTE (TD-LTE) to provide a wireless voice and data service at 3.5 GHz (3550 MHz to 3700 MHz). The radio interface is identical to LTE at other frequencies, thereby supporting voice, text and data services with seamless mobility. It is governed by a three-tiered spectrum authorization framework to accommodate a variety of commercial uses on a shared basis with incumbent federal and non-federal users of the band. Access and operations will be managed by a dynamic, tiered, spectrum access system. The three tiers are Incumbent Access, Priority Access, and General Authorized Access: • INCUMBENT ACCESS includes mainly U.S. Naval Radar. • PRIORITY ACCESS means an organization can pay a fee for a Priority Access License (PAL). Each PAL is defined as a non-renewable authorization to use a 10-megahertz channel in a single census tract for three years. • GENERAL AUTHORIZED ACCESS (GAA) is licensed-by-rule to permit open and flexible access to the band for the widest possible group of potential users. This GAA tier is slated for use by enterprise customers. In the future, OEMS will develop cloud-RAN solutions where virtualized servers and software drive down further the overall cost and complexity of in-building networks.